I have both X400 and TLR-2s light/laser units. I think the X400 is definitely a better design. The paddle switch to activate is pretty much a wash, but the selector switch on the X400 is superior IMHO since it allows you to turn the unit off to prevent inadvertently triggering it. The TLR has a 3-position toggle that is pretty exposed and only lets you choose light, laser, or both. The X400 is noticeably brighter at distance. I have no trouble lighting up the side of a building at night that is 50m away, and seeing the laser dot. As such, the X400 becomes a viable light/laser option on a carbine. Depending on the target material, the laser on the X400 is visible even in bright sunlight at pistol distances.
The light on the TLR-2s is brighter than on the original TLR-2, and while it doesn't punch out as far as the X400 it diffuses well to light up a room. I found the adjustment range on the TLR to be greater than on the X400.